1. Field of the Invention
The present invention relates to a packaging structure of a light-sensing device, particularly to a packaging structure of a light-sensing device with a spacer wall.
2. Description of the Related Art
With the wide popularity of audio/video multimedia, the digitization of images is a consequential trend, and the appearance of digital cameras, digital video cameras and image scanners signifies the arrival of the image-digitization age. CMOS (Complementary Metal Oxide Semiconductor) is a key technology for image digitization, and the quality, yield and cost thereof are critical factories in the campaign of image digitization.
Refer to FIG. 1 a diagram schematically showing a conventional packaging structure of a CMOS image sensor. The conventional packaging structure comprises: a light transparent substrate 10, which has multiple metallic traces 12 and multiple metallic balls 14 used to form the electric connection with the metallic traces 12; a light-sensing element 16, having a light-sensing region 18 and multiple metallic pads 20, wherein the light-sensing element 16 is installed to the substrate 10 via multiple metallic contacts 22 and those metallic contacts 22 are also used to electrically interconnect the light-sensing element 16 and the metallic traces 12 of the substrate 10; and a glue layer 17, disposed between the substrate 10 and the light-sensing element 16, used to seal the gap between the substrate 10 and the light-sensing element 16 and used to protect the light-sensing region from external pollutants.
However, when the glue is applied to the abovementioned packaging structure, owing to the fluidity of the glue, the glue will overflow into the neighboring regions and incurs some problems. For example, when the metallic pads 20 are disposed too much close to the light-sensing region 18, the glue will overflow into the light-sensing region 18, which will influence the function of the light-sensing element 16; when the metallic pads 20 are disposed too much close to the metallic balls 14, the metallic balls 14 will be polluted by the overflow glue. When those metallic balls are processed with an SMT (Surface Mount Technology) infrared reflow, the yield loss will occur. As it is a current trend to fabricate slim and lightweight multimedia products, the spacing between the metallic pad 20 and the metallic ball 14 becomes more and more small; thus, the pollution problem becomes further serious, and the yield and quality is obviously influenced.
Accordingly, the present invention proposes a packaging structure of a light-sensing device with a spacer wall to overcome the abovementioned problems and promote the competitiveness.